Infrared spectroscopic analysis of biomedical specimens using glass substrates

We report on the use of glass substrates for the infrared spectroscopic analysis of dried serum, amniotic fluid, and synovial fluid films. New analytical applications of infrared spectroscopy are emerging rapidly, spurred largely by ever-improving instrumentation, combined with the widespread availability of powerful chemometric methods. We have recently begun to focus upon potential applications in both clinical chemistry and medical diagnostics. For example, serum analysis, the determination of fetal lung maturity, and the differential diagnosis of arthritis have all recently been demonstrated to be feasible on the basis of the infrared spectra of films dried from the appropriate samples (serum, amniotic fluid, or synovial fluid). However, the transition from the laboratory into clinical usage hinges on the availability of IR-transparent substrates that are both inexpensive and readily obtainable. We have demonstrated in this study that despite limited transparency in the IR region, clinical analyses and diagnostic spectral classifications may nevertheless be carried out using glass as a substrate for the IR measurements.